Electric regulation



y 9, 1935- a. E. HULSE I ELECTRIC REGULATION 2 Sheets- 511951; 1

Filed Nov. 20, 1931 BY ATTOR NEY:

July 9, 1935. HULSE 2,007,760

ELECTRIC REGULATION Filed Nov. 20, 1931 2 Sheets-Sheet 2 BY ATTORNEYS Patented July 9, 1935 UNITED STATES PATENT OFFICE ELECTRIC REGULATION Application November 20, 1931, Serial No. 576,283

Claims.

This invention relates to electric regulation and more particularly to an electric regulator embodying a variable resistance with suitable operating mechanism and to the method of making 5 such a variable resistance.

One of the objects of this invention is to provide a regulator for use in electric circuits that will be of simple and thoroughly practical construction, highly eflicient action, and well adapted to meet the widely varying conditions of hard practical use. Another object is to provide a regulator having a resistance medium that is variable in accordance with the pressure exerted thereon and in which the many deficiencies and disadvantages of the heretofore known compressible carbon pile type of regulator are dependably and inexpensively overcome. Another object is to provide a regulator of the above-mentioned character in which a. greater range of change of resistance and hence a greater range of regulation may be achieved for the same or for a less amount of energy required to operate the regulator than has heretofore been possible. Another object is to provide a regulating apparatus of the abovementioned character in which greater compactness of construction, greater sensitiveness and accuracy of regulation, and the use of a lesser amount of material either in the resistance medium itself or in the operating system therefor or both may be dependably and inexpensively achieved. Another object is to provide a regulating apparatus of the above-mentioned type that will have a greater range of application and that will be capable of a greater variety of manner of use than has been possible with known types of pressure-controlled resistance regulators. Another object is to provide a simple and thoroughly practical method of making the pressure-controlled resistance element and one that may be readily and inexpensively carried on in practice. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts and in the several steps and relation and order of each of said steps to one or more of the others thereof, all as will be herein illustratively described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which are shown several of various possible embodiments of certain mechanical features of my invention,

Figure 1 is a front elevation, partly diagrammatic and partly in vertical central section, of

a regulator, an illustrative circuit in which it is adapted to function being diagrammatically shown;

Figure. 2 is a vertical sectional view as seen along the line 2-2 of Figure 1;

Figure 3 is a front elevation of a regulator, with an illustrative circuit in which it is adapted to function shown diagrammatically, illustrating certain other features of my invention;

Figure 4 is an elevation of an end plate and a part of a resistance element, illustrating a possible mode of mechanical connection therebetween;

Figure 5 is an end view as seen from the left in Figure 4;

Figure 6 is a diagrammatic plan view, partly in horizontal section, showing a possible step in my method of producing the resistance element, and

Figure 7 is a plan view partly in horizontal section illustrating diagrammatically a possible way of carrying out another step in my method.

Similar reference characters refer to similar parts throughout the several views in the drawings.

As conducive to a clearer and more ready understanding of certain features of my invention, it may at this point be noted that the usual or known type of compressible carbon pile variable resistance, made up of a series or stack of carbon plates generally in the form of disks, has a great many advantages in practical use but is inherently characterized by a number of disadvantages and shortcomings which it has heretofore been impossible to eliminate. For example, it has been found that in such carbon pile resistances the few plates at the movable end of the pile have imposed upon them the major part of the work to be done, particularly when the resistance of the pile is to be increased toward its upper limit and that sparking and arcing frequently occur at these end plates with the result that the latter are harmed and must be frequently replaced.

Another and vital difficulty with known carbon piles resides in the fact that, to make such piles function throughout their intended range, the plates or disks of which they are composed have to be given individually a certain curvature or warping in order thus to achieve greater or appropriate variation in contact areas and in pressure of contact; in such cases, in order to achieve the minimum resistance of which the carbon pile is to be capable of presenting to the circuit in which it is included, relatively very great forces of compression have to be employed with the result that heavy springs, heavy and sometimes complicated systems of force-transmission, have to be employed, and the solenoids or electromagnets controlling these parts have to be made correspondingly very heavy, large, and powerful.

By way of illustration, let it be assumed that a compressible carbon pile regulator is to function throughout a range of change of resistance from a minimum of 0.1 ohm to a maximum of 4.5 ohms. This requirement may be met, with this known type of regulator, if fifty carbon disks each oneeighth of an inch thick and two and five-elghths of an inch in diameter are arranged ina suitable stack or face to face. These disks, however, have to be curved slightly in a direction transversely of their plane and if the minimum resistance of 0.1 ohm is to be achieved a pressure of twenty pounds has to be applied to compress these fifty carbon disks sufiiciently to achieve this minimum resistance. This very high force may be provided by a spring or by a suitable multiplying system of levers and inany event has to be opposed by the pull of the solenoid or electromagnet winding. The latter has to be correspondingly large and a relatively great change of current has to take place therein to achieve the desired regulating action. I

One of the dominant aims of this invention is to provide a variable pressure responsive carbon resistance in which such disadvantages as those just noted above may be dependably eliminated and a great many advantagesachieved in a simple, inexpensive, and practical way.

Turning now to the drawings and more particularly to Figure l, I have there shown diagrammatically/and purely by way of illustration and not by way of limitation, an electrical system such as is used in lighting railway cars; that system may include a generator I0 driven, for example, from the car axle and adapted to supply current to a storage battery II and to the lamps 82, these parts being connected across the main line conductors l3'l4 and the connection of the generator H! to the battery II and lamp load l2 being achieved by any suitable form of automatic main switch diagrammatically indicated at l5.

By way of illustration, the battery ll may be a l6-cell battery and the lamps l2 may be intended to operate at a voltage of thirty volts. The voltage of the storage battery varies throughout relatively wide ranges, depending upon its state of charge and depending also upon whether or not the generator I0 is connected thereto and is charging the battery. The voltage across the battery I! may, for example, rise to a value as high as-forty volts, forty-two volts, or the like, and to prevent voltages in excess of normal lamp voltage from being applied to the lamps, there is interposed between the' battery and the lamps a variable resistance controlled by a voltage responsive coil, connected across the lamp circuit, to maintain a sufficient IR drop in the line at all times to maintain substantial constancy of voltage across the lamp at the normal or' intended lamp voltage.

Under certain circumstances,- such a regulator is called upon to produce a maximum resistance of 4.5 ohms and a minimum resistance below 0.1 ohm. The carbon pile regulator above-described and made up of fifty carbon disks, if inserted in this circuit, would have to be capable of exerting a pressure of at least twenty pounds on the car- In accordance, however, with certain features of my invention, I interpose between the battery". H and the lamps 12 a pressure-responsive variable resistance in which I can achieve a still lower minimum resistance while requiring only a relatively small fraction of the maximum pressure that is inherent in known forms of carbon pile resistances.

Mounted upon a suitable vertically extending panel it are two brackets or supports Ill8 preferably shaped as is better shown in Figure 2 in which the bracket I8 is seen in side elevation. Brackets l1 and 18 are spaced apart and support four members I9, 20, 2! and 22, of non-conducting material, such as porcelain, which extend from the bracket H to the bracket l8, being arranged, as is better shown in Figure 2, at the apexes of a square or about a circle. These members may be and preferably are in the form of porcelain tubes and may function as spacers, fitting in between the brackets I1 and i8, the parts being rigidly held together and in aline'ment by bolts 23 that pass through the brackets and through the tubular insulating members. a.

Loosely supported by the porcelain supporting members 59, 20, 2| and 22, is a resistance element generally indicated at 24, member 24 being in the form of a helix of carbon ribbon and having an outside diameter small enough to let itbe relatively loosely received (see Figure 2) between and supported by the porcelain tubes.

To better understand the construction and nature of resistance element 24 reference may'now be made to Figures 6 and '7. Member 24 is preferably made of a material similar to that heretofore employed in compressible carbon disk variable resistances and a preferred manner of making member 24 consists in first making up a rod of carbon and then boring it out to form .a tube or to-form the carbon material initially in the form of a tube. In Figure 6 I have indicated such a tube at 25 and I have shown it mounted and supported for rotation by any suitable device or chuck 26, and the latter is mounted in a lathe or screwcutting machine. Thus, I achieve'a suitable rate construction and action, I have exaggerated the width of the cutting tool 21 and likewise exaggerated the width of the helical groove. Preferably, the width of the cutting tool 21 is made as small as practical conditions permit and the width of the helical groove is likewise correspondingly small, but these factors may be varied, as will be more clearly pointed out hereinafter, depending upon practical conditions to be met. As many traverses of the tool 21 in a direction from the right to the left (in Figure 6) may be made as may be necessary to achieve the relative depth of cut indicated in the cross-sectional portion of is provided a helicaliy shaped flange or rib the adjacent convolutions of which are joined by a relatively thin wall 23 adjacent the bore of the tube 25.

' Having completed the step above-described in connection with Figure 6, the tool 21 is replaced by a tool, such as that indicated at 23 in Figure 7; tool 23 is shaped to enter the bore 01' tube 25 as it turns the latter down from the inside and, as the tube 25 is rotated, tool 21 is advanced toward the left, as viewed in Figure 7, thus to remove the joining wall portions 25 which connect the helical flange or rib 25', leaving a helical ribbon 24. During this operation, a tube 45, preferably of metal and snugly iltted over the member 25, steadies the latter during the cutting action by tool 21. As many cuts or traverses of the boring tool 28 in a direction from the right to the left (in Figure 7) may be made as circumstances require to achieve the removal of the connecting portions 25.

In the illustrative preferred form thus achieved, the cross-section of the helical ribbon is substantially rectangular, as appears clearly from Figures '7 and 1; the adjacent faces of successive convolutions of the helical ribbon are parallel and preferably plane so that when the helix is compressed, against its own resiliency and against its tendency to remain in its normal/expanded form, the face of one convolution nicely mates with the contiguous face of the adjacent convolution and a uniform surface contact throughout the entire helix is thus achieved.

This helix is inserted in between and is carried by the porcelain supports I8, 20, 2| and 22 (see Figures 1 and 2). Its left-hand end abuts and rests against an annular plate member 29 preferably of metal and suitably held against movement in a direction toward the left. Conveniently, bracket I! may act to limit movement of;

the member 29 toward the left and for this purpose a. suitable annular insulating member 30 made, for example, of porcelain, may be interposed between the metal end plate 29 and the bracket l'l.

At the right-hand end, the helix 24 is engaged by an annular metal plate 3| dimensioned so that t may slide along the porcelain supporting rods I9, 20, 2| and 22 and metal end plate 3| is engaged by the arms 32* and 32 (see Figure 2) of the forked upper end of arm 33 of a lever pivoted to the panel l6 at 34 and having an arm 35 extending to the left and to the right of the pivot 34 (see Figure 1).

A spring 36 acts upon the right-hand end of arm 35 and swings the lever 35-33 in counterclockwise direction, thus to compress the carbon helix 24, and its action is opposed and controlled by a suitable electromagnetic means that may illustratively and conveniently take the form of a solenoid having a winding 3'! which acts upon a movable plunger or core 33 suitably connected to the left-hand end of arm 35 of the lever.

The carbon helix 24 is connected into the circuit in which it is to function by attaching, in any suitable manner, the conductors of the circuit to the metal end plates 23 and 3|.

Where the regulator is intended to operate in response to changes in voltage, as in the illustrative electrical system above described in connection with Figure 1, winding 31 is wound to be voltage-responsive and in the specific illustrative system the parts are so constructed and related that winding 31 can hold the solenoid core 33 in any position throughout its operative range of movement when the winding is energized by the intended or desired voltage to be held across the lamps l2. Where the electromagnetic means is in the form of a solenoid, the

core 33 may be tapered at its upper end, as at 38, and may coact with a correspondingly but interiorly taperecl fixed magnetic core part 33 (see Figure 1).

Assuming, in the illustrative circuit abovedescribed, that a maximum of 4.5 ohms and a minimum resistance of at least 0.1 ohm must be achieved by the regulator, I find that I can achieve this range where the carbon helix 24 has an outside diameter of one and seven-eighths of an inch and an inside diameter of one and one-eighth of an inch with the ribbon of the helix one-eighth of an inch thick and comprising thirty-three complete turns; this with carbon having a specific resistance or resistivity of 0.0018 ohm per cubic inch, a resistivity substantially identical with that of the compressible carbon disk regulator hereinabove described. But instead of requiring twenty pounds or more of pressure to achieve the minimum resistance of 0.1 ohm, as was the case with the latter regulator, I am enabled, with the construction of my invention, to achieve a lesser minimum, namely, 0.074 ohm with a pressure of only live pounds upon the helix.

For example, when the voltage of the battery II is low so that the very minimum of resistance should be interposed between it and the lamps I2, the best prior known compressible resistance requires a force of compression of twenty pounds or more to achieve a minimum of 0.1 ohm but with my invention I am enabled under these conditions to obtain a far lesser minimum value of resistance with a far less applied pressure. The spring in my apparatus need be only a fraction as powerful as in prior practice and the same is true of the electromagnetic means such as the electromagnet or solenoid, for example, while I am further enabled to use a far less powerful mechanical system through which the electromagnetic means and/or spring operate. I am thus enabled to achieve far greater sensitiveness of regulation and to achieve this and many other results with an energy consumption in the electromagnetic means vastly less than has been necessary in prior practice.

Moreover, I achieve also many other farreaching advantages. For example, the helix 24 is inherently resilient, acting in the nature of a helical spring opposing, but in a relatively small measure only, the force applied to its free end in the direction of compression. At all positions of the lever 33-35 throughout its operative range, this inherent resiliency of the carbon helix 24 insures uniformity of action throughout the entire resistance element no matter what the degree of compression of the convolutions of the ribbon against each other may be, for that pressure is the same throughout the length of the helix and this is particularly important when the device is called upon to approach or reach the maximum ohmic resistance. The convolutions of the helix 24 are in a physical sense substantially self-sustaining and, because of the inherent resiliency of the helix, any looseness of contact between adjacent convolutions in these upper ranges of ohmic resistance is the same and hence uniform throughout the entire length of the helix.

Thus, the electrical energy which the resistance is called upon to dissipate in the form of heat is uniformly distributed throughout the length of the helix and each portion thereof does an equal amount of work. There'is thus no possibility of unequal distribution of energy losses with the result that long life is assured.

Moreover, the possibility of arcing or sparking, of such common occurrence in known compressible carbon pile resistances, is entirely eliminated for, irrespective of the pressure of contact between adjacent convolutions, the helical ribbon forms a continuous helical path for the current which cannot be interrupted to cause sparking or arcing.

To facilitate the achievement of this latter action, the inherent resiliency of the helix and its tendency to expand may be utilized to insure the maintenance, at all times, of a dependable electrical contact between the end. convolutions and the metallic end plates 29 and 3! by means of which the variable resistor is included or connected into the circuit in which it is to function. Particularly is this action highly advantageous and important when the maximum resistance is desired, for in the carbon pile type of regulator, the looser that the contacting parts become, the

. place between loosened parts.

Thus, the wearing out of the resistance medium or portions thereof, by sparking, arcing, or the like, is virtually precluded and no replacement of individual parts is necessary.

These and many other advantages will be seen to be achieved also with the use of far less resistance material than would otherwise be the case. In the specific illustrative example above set forth, note the comparison of the mass of carbon utilized in the ribbon 24 with the mass of fifty carbon disks of vastly greater diameter necessary to achieve a commensurate range of change of resistance in accordance with prior practice.

As a result of such features of my invention as have above been noted, the regulating apparatus may be made much smaller and much lighter and hence less expensive, while at the same time I achieve greater sensitiveness of action and control, the much smaller weight of moving parts having such vastly less inertia as compared to prior practice that a higher degree of accuracy of regulation with greater sensitive ness of action and less consumption of energy may be reliably achieved.

Referring again to Figures 1 and 2, itwill be noted that the metal end plates 29 and 3! and coacting parts, such as the insulating washer 30 and the brackets I! and i8, are constructed so that the inner edge faces of the helical ribbon 24 are exposed to the atmosphere just as are the outer edgefaces. Thus, I am enabled to achieve effective heat radiation and to prevent undue or undesired heating of the resistance member 24. Also, when the regulator is operating throughout its upper ranges of resistance, when the convolutions are but lightly contacting with each other or even when they may be virtually separated, the inherent resiliency of the helix achieves uniform spacing between adjacent convolutions so that heat dissipation from the side faces of the latter may uniformly take place throughout the entire length of the helix.

In order to achieve more rapid heat dissipation and other advantages, I may arrange the axis of the helix virtually as in Figure 3, instead of horizontally as in Figure 1. In Figure 3 the lower end of the helix 24 is provided with an end plate 29 suitably secured to an annular support 40, while the other end plate 3| is secured to the forked arms 4! and Bi of a lever 4| pivoted as at 42 and controlled by the opposing actions of spring 35 and electromagnetic means in the form illustratively of the solenoid 3! operating upon the movable plunger or core 38.

Preferably the end plates 3| and 29 are secured to the ends of the helix 24 in any suitable manner, for example, as is shown in Figures .4 and 5, in which suitable fastening devices 43 which may take the form of rivets, pins, or the like, effect a connection between the parts, or, by cementing.

with the arrangement of Figure 3, many thoroughly practical advantages are achieved and themany deficiencies of prior attempts to devise and successfully operate a carbon pile variable resistance are dependably eliminated. In such prior attempts, there is a detrimental non-uniform distribution of the work done by the carbon pile because the lower plates or disks are compressed by the weight of the upper disks. With my invention, however, such a disadvantage does not occur because'of the inherent resiliency of the carbon helix-and its resultant inherent tendency to expand.

In the arrangement of Figure 3,, therefore, if the electromagnetic means and related parts require an increase in the resistance in the circuit and hence effect a movement of the upper plate 38 in an upward direction, the contact pressure between adjacent convolutions 'is diminished substantiallynuniformly throughout the length of the vertical helix for every convolution takes part in the movement of the upper end plate 3|. Furthermore, this vertical arrangement insures very effective cooling for convection air currents can freely and readily move upwardly along both the exterior and interior faces of the helix 24, the latter in effect forming a flue for efiiciently carry g on such cooling by convection air eurrents.

It is to be understood that I do not wish my invention to be limited to the specific numerical figures, dimensions, or the like, above set forth in connection with either Figure 1 or 3, or to the circuit arrangement shown in Figure 1, and that such data as has been set forth is purely illustrative of one of many possible embodiments of my invention and may be widely varied to meet the varying conditions'of' practical use.

I have above pointed out that the material I employ is preferably the same material that -is now employed in making up the carbon plates or disks of known forms of compressible carbon piles. Such a material I have found has a sufficient inherent resilience to achieve such actions and advantages as have been pointed out above in connection therewith. I may note, however, that I may otherwise vary the resiliency of the carbon helix by correspondingly varying the width of the cutting tool, such as the cutting tool 21 of Figure 6, so as correspondingly to vary the width of the helical groove that it cuts. The wider that I make this groove, the greater is the inherent force in the helical ribbon that brings about the separation of adjacent convolutions when the pressure bringing about the contact between adjacent convolutions is removed.

An important feature of construction and action resides in the fact that I make it possible to avoid the chance of actually interrupting or a helix so that its convolutions are out of contact with each other leaves in the circuit a continuous conductor, namely, the carbon ribbon itself, and the maximum resistance presented to the circuit is thus the resistance of this ribbon per se. With the known compressible carbon pile, there is always the danger of actually interrupting the circuit when the carbon disks are completely loosened up, to say nothing of the sparking and arcing that result in the process. Also, the maximum resistance in such known carbon piles is a very variable factor oftentimes, while with my apparatus the maximum resistance achieved may be always a definite ohmic value.

It will thus be seen that there has been provided in this invention a method and apparatus in which the various objects hereinbefore set forth, together with many thoroughly practical advantages, are successfully achieved. It will be noted that I am enabled to achieve greater ranges of change of resistance with apparatus using less material and more economically than has heretofore been possible and that, in particular, I am enabled to achieve 'wide ranges of change of resistance with the application of forces that are but a small fraction of those that it has heretofore been necessary to employ. Moreover, I am enabled to achieve greater sensitiveness of action, perfect uniformity of distribution of work, and long life. Furthermore, it will be seen that the apparatus is well adapted to meet the varying conditions of hard practical use.

As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood that all matter her'einabove set forth or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a system of electric regulation, in combination, a source of current, a work circuit, regulating means including a coil and a member moved thereby, said coil being'responsive to a function of the energy supplied by said source to said work circuit, said coil being energized by energy received from said source, a spring opposing the action of said coil, and a pressure responsive resistance comprising a plurality of contacting carbon parts affected by both said member and said spring and constructed for uniform heat dissipation throughout and for minimizing the force of compression as determined by said member and said spring required to achieve a minimum value of resistance, said parts comprising the con- .volutions of a carbon helix having uniform crossmoved thereby, said coil being responsive to a function of the energy supplied by said source to said work circuit, said coil being energized by energy received from said source, a spring opposing the action of said coil, and a pressure responsive resistance comprising a plurality of contacting carbon parts affected by both said member and said spring and constructed so that, throughout all ranges of change of resistance thereof, each part does substantially the same amount of electrical work, said parts comprising the convolutions of a carbon'helix of uniform inside and outside diameters throughout and of uniform crosssection throughout, the cross-section of the said parts being of uniform area and the convolutions of the helix having such a pitch that, for any relative positions of said member and said spring, the contact pressure between adjacent convolutions is uniform throughout.

3. In an electric system of distribution of the class wherein a source of electrical energy supplies current to a work circuit and a pressureresponsive resistance made up of a plurality of contacting carbon parts with means for controlling the pressure of compression of said carbon parts comprising a coil responsive to a function of the energy supplied by said source, a member moved by said coil and operating upon said parts and a spring opposing the action of said coil, the combination, for preventing sparking between certain of said parts when the compression thereon is lessened and for causing said parts to do the same amount of electrical work throughout the-range of change of compression thereon, with said coil, member, and spring, of a pressure responsive carbon resistance in which the parts comprise the connected convolutions of a helical ribbon of carbon, said ribbon being of uniform cross-section throughout and having a uniform pitch for any stage of compression, whereby the helix has a uniform spring action and the pressure of contact between adjacent convolutions for any stage of compression or the space between adjacent convolutions for any stage after said member and said spring achieve absence of compression is uniform throughout.

4. A variable pressure-responsive resistance made up of a plurality of contacting carbon parts for insertion into an electric circuit and for use in-connection with means for controlling the pressure of compression of said carbon parts, in which the said parts comprise the connected convolutions of a helical ribbon of carbon, said ribbon being of uniform cross-section throughout and having a uniform pitch for any stage of compression effected by said controlling means andthe resultant helix having a uniform spring action and the pressure of contact between adjacent convolutions for any stage of compression or the space between adjacent convolutions for any stage after said means achieves absence of compression being uniform throughout;

5. A variable pressure-responsive resistance made up of a plurality of contacting carbon parts for insertion into an electric circuit and for use in connection with means for controlling the pressure of compression of said carbon parts, said resistance being constructed so that, throughout all ranges of change of resistance thereof, each part does substantially the same amount of electrical work, said parts comprising the convolutions of a carbon helix having uniform cross-section and uniform tendency to expand in the direction of its axis, whereby for any stage of compression of said parts as effected by'said means the contact pressure between adjacent parts is uniform and the resistance drop effected by said resistance in the said circuit is uniform along the helix.

GEORGE E. HUISE. 

